The present invention relates generally to wavelength division multiplexing and, more particularly, to a technique for detecting the status of wavelength division multiplexed optical signals.
As the use of wavelength division multiplexing (WDM) technology grows, the use of WDM will evolve from simple, isolated point-to-point systems to interconnected systems such as metro rings, WANs, and CANs. In order for systems to be able to connect and communicate together, they will require many new types of optical add-drop multiplexers, fiber switches, and wavelength optical switches. Due to the typical requirement that a network always be 100% reliable, there will be a great need to verify that individual signal channels have optical signals on them, as well as the power level of each optical signal. For example, at an add-drop multiplexer node, there is a real need to determine if an optical switch has correctly operated to drop traffic to the node. Similarly, there is a real need to measure the power in each optical signal either before or after an erbium-doped fiber amplifier (EDFA) to ensure that the gain is equal across all signal channels.
At present, devices for detecting the presence and power of wavelength division multiplexed optical signals are not widely available primarily because the commercial use of WDM systems is new and most signal restoration and monitoring is performed down on the electronic level as part of a synchronous optical network (SONET), or other, protocol. Consequently, devices for detecting the presence and power of wavelength division multiplexed optical signals that are presently available such as, for example, optical spectrum analyzers, are typically very costly (e.g., over $10K per device). Also, some devices that are presently available for detecting the presence and power of wavelength division multiplexed optical signals may adversely affect the data that is being transmitted by the wavelength division multiplexed optical signals. That is, some devices that are presently available for detecting the presence and power of wavelength division multiplexed optical signals operate by intercepting the wavelength division multiplexed optical signals when detecting signal presence and power. The wavelength division multiplexed optical signals are then typically retransmitted after detecting signal presence and power. Inherent in the interception and retransmission operations are many opportunities for failure which can adversely affect the data that is being transmitted by the wavelength division multiplexed optical signals.
In view of the foregoing, it would be desirable to provide a technique for detecting the presence and power of wavelength division multiplexed optical signals which overcomes the above-described inadequacies and shortcomings. More particularly, it would be desirable to provide a technique for detecting the status of wavelength division multiplexed optical signals in an efficient and cost effective manner.
The primary object of the present invention is to provide a technique for detecting the status of wavelength division multiplexed optical signals.
The above-stated primary object, as well as other objects, features, and advantages, of the present invention will become readily apparent from the following detailed description which is to be read in conjunction with the appended drawings.
According to the present invention, a technique for detecting the status of wavelength division multiplexed optical signals is provided. In a preferred embodiment, the technique is realized by first splitting an original, multiplexed, polychromatic optical beam into at least two representative, multiplexed, polychromatic optical beams. Next, a first of the at least two representative, multiplexed, polychromatic optical beams is separated according to wavelength into a plurality of optical signal channels. Each of the plurality of optical signal channels is for communicating a respective, representative optical signal via a respective, representative, discrete, monochromatic optical beam, wherein each representative optical signal is representative of a corresponding optical signal in the original, multiplexed, polychromatic optical beam. Finally, the presence or absence of a representative optical signal is detected on each of the plurality of optical signal channels.
In accordance with other aspects of the present invention, the original, multiplexed, polychromatic optical beam is beneficially split according to optical beam power. For example, the first representative, multiplexed, polychromatic optical beam preferably includes less than approximately 1% of the power of the original, multiplexed, polychromatic optical beam.
In accordance with further aspects of the present invention, the first representative, multiplexed, polychromatic optical beam is beneficially separated by demultiplexing the first representative, multiplexed, polychromatic optical beam. For example, the first representative, multiplexed, polychromatic optical beam is preferably collimated and then separated into the plurality of optical signal channels for communicating respective, representative optical signals via respective, representative, discrete, monochromatic optical beams. Each representative, discrete, monochromatic optical beam is then preferably focused onto a corresponding detector. The first representative, multiplexed, polychromatic optical beam is preferably reflected during the demultiplexing process. Alternatively, each representative, discrete, monochromatic optical beam may be reflected during the demultiplexing process.
In accordance with still further aspects of the present invention, it may be beneficial to sense the power of a representative optical signal that is present on each of the plurality of optical signal channels. The power of a representative optical signal is preferably sensed by sensing the intensity of a corresponding representative, discrete, monochromatic optical beam that is present on one of the plurality of optical signal channels.